Grobīs Attack, also known as the Spike, is an unconventional (ECO code A00) chess opening where White immediately moves the king knightīs pawn two squares ahead: 1.g4.

The opening takes its name from Swiss International Master Henry Grob (1904–1974) who analyzed it extensively and played hundreds of correspondence games with it. Early references used the name Ahlhausenīs Opening, after Carl Ahlhausen (1835–1892) of Berlin, one of the first to play 1.g4. Ksawery Tartakower sometimes played this opening in simultaneous exhibitions and called it the Genoa or San Pier DīArena Opening, after the city and suburb of Genoa where he first used it. In Czechoslovakia 1.g4 is called Fricīs Opening, and in other parts of the world it is called Kolibriīs Opening.

The Grob is considered inferior and is usually not employed in serious competition, although International Master Michael Basman is an advocate. It does, however, have a certain surprise value and the average player is unlikely to know how to refute it and more likely to get overconfident and make mistakes. Intuititive play by black can lead into dangerous traps. Many of these traps rely on Blackīs replying with 1.... d5, attacking the pawn with his queenīs bishop. After 2.Bg2 Bxg4?, White has an attack after 3.c4 and eventually Qb3, an attack that may well be worth a pawn.

Many Grob players enjoy the (self-)destructive nature of the opening. By immediately moving the g-pawn two squares ahead White is really saying: "I am going to rip apart the pawn structure in this game — first mine, then yours."

A key element of the Grob is deploying the kingīs bishop on g2 and having it rule the diagonal. In order to further this goal white must keep the center clear of pawns. This leads to frequent "tearing at the center" with c4 often being whiteīs second move. This further adds to the violent and destructive nature of the Grob game.

Due to the freakish pawn structure white attains by playing g4 and c4 so early in the game there is frequently little advantage to castling — indeed the king may be safest in the center!